"There are traditions that seem as though they’ve always been in place. Some of them have origins that are obscured by time, but others can be assigned to a particular time and person. The tradition of representing the new year with the image of a baby is one of the latter.

"In addition to helping codify the modern image of Santa Claus, the great Golden Age illustrator J.C. Leyendecker originated the idea of using a baby to symbolize the birth of the new year. 

"Starting with a Saturday Evening Post cover in 1906 for which he painted a winged cherub that was close to the idea, he began using an actual baby in the December, 1907 issue to welcome in 1908; and continued to represent the coming year that way on New Year’s covers of the Post into the 1940’s. 

"Leyendecker was the Post’s major artist in the first half of the 20th Century, and was routinely given the assignments for the important major holiday issues. It was only years later that Norman Rockwell, who considered Leyendecker his artistic ideal, began to take on those duties."

Article: Happy Leyendecker Baby New Year!